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United States Patent |
5,540,769
|
Franz
,   et al.
|
July 30, 1996
|
Platelet-like colored pigments and process for producing the same
Abstract
Platelet-shaped colored pigments containing titanium dioxide, one or more
suboxides of titanium and an oxide or oxides of one or more metals other
than titanium or non-metals and a process for the preparation thereof is
disclosed.
Inventors:
|
Franz; Klaus-Dieter (Kelkheim, DE);
Ambrosius; Klaus (Dieburg, DE);
Wilhelm; Stefan (Heppenheim, DE);
Nitta; Katsuhisa (Fukushima, JP)
|
Assignee:
|
Merck Patent Gesellschaft Mit Beschrankter Haftung (Darmstadt, DE)
|
Appl. No.:
|
307695 |
Filed:
|
September 23, 1994 |
PCT Filed:
|
March 16, 1993
|
PCT NO:
|
PCT/EP93/00617
|
371 Date:
|
September 23, 1994
|
102(e) Date:
|
September 23, 1994
|
PCT PUB.NO.:
|
WO93/19131 |
PCT PUB. Date:
|
September 30, 1993 |
Foreign Application Priority Data
| Mar 26, 1992[DE] | 92 105 213.0 |
Current U.S. Class: |
106/415; 106/436; 106/442; 106/DIG.3; 428/363; 428/402 |
Intern'l Class: |
C04B 014/04; C04B 014/20; C04B 014/10; C04B 014/22 |
Field of Search: |
106/415,417,436,442,DIG. 3
428/363,402
|
References Cited
U.S. Patent Documents
4450012 | May., 1984 | Messer et al. | 106/442.
|
4623396 | Nov., 1986 | Kimura et al. | 106/417.
|
4828623 | May., 1989 | Nitta et al. | 106/417.
|
4948631 | Aug., 1990 | Ostertag et al. | 106/417.
|
5118352 | Jun., 1992 | Noguchi | 106/415.
|
Foreign Patent Documents |
0332071 | Sep., 1989 | EP.
| |
0354374 | Feb., 1990 | EP.
| |
3433657 | Mar., 1985 | DE.
| |
62-295979 | Jun., 1989 | JP.
| |
Other References
Abstract of JP 58 164 653 Sep. 29, 1983.
Abstract of JP 3,079,673. Mar. 31, 1992.
Abstract of JP 59 126 468. Jul. 21, 1984.
Database WPIL, Section Ch, Week 8345, Derwent Publications Ltd., London,
GB; Class E32, AN 83-810901 (abstract of JP-A-58 164 653). Sep. 29, 1983.
|
Primary Examiner: Group; Karl
Assistant Examiner: Marcheschi; Michael
Attorney, Agent or Firm: Millen, White, Zelano & Branigan, P.C.
Claims
We claim:
1. A platelet-shaped colored pigment comprising a platelet-shaped substrate
coated with a coating layer consisting of
50-99% by weight of titanium oxides including titanium dioxide and at least
one suboxide of titanium and
1-50% by weight of silica,
such that the coating layer has a surface adjacent to the substrate and an
outer surface, wherein the concentration of the titanium oxides in the
coating layer is maximum at the surface adjacent to the substrate and
gradually decreases towards the outer surface, and the concentration of
silica is maximum at the outer surface and gradually decreases towards the
surface adjacent the substrate.
2. The pigment of claim 1, wherein the coating layer consists of
70-98% by weight of the titanium oxides and
2-30% by weight of silica.
3. The pigment of claim 1, wherein the platelet-shaped substrate is a mica,
kaolin or glass platelet optionally coated with one or more metal oxide
layers or a metal or metal oxide platelet coated with TiO.sub.2.
4. The pigment of claim 1, wherein the substrate has a diameter of 1 to 500
.mu.m and thickness of 0.1 to 1 .mu.m.
5. A process for preparing a platelet-shaped colored pigment, which
comprises mixing a platelet-shaped substrate coated with TiO.sub.2 with Si
powder as a solid reducing agent to form a mixture and heating the mixture
in a non oxidizing atmosphere at a temperature of more than 600.degree. C.
6. The process of claim 5, wherein said substrate coated with TiO.sub.2 and
said Si powder are mixed in a weight ratio from 200:1 to 5:1.
7. The process of claim 5, wherein said substrate coated with TiO.sub.2 and
said Si powder are mixed in a weight ratio from 100:1 to 10:1.
8. The process of claim 5, wherein a halide is admixed with said
platelet-shaped substrate coated with TiO.sub.2 in an amount of from 0.1
to 40% by weight of the substrate coated with TiO.sub.2.
9. The process of claim 8, wherein said halide is admixed with said
platelet-shaped substrate coated with TiO.sub.2 in an amount of from 0.5
to 10% by weight of the substrate coated with TiO.sub.2.
10. The process of claim 8, wherein said halide is MgCl.sub.2, CaCl.sub.2
or CeCl.sub.3.
11. The process of claim 6, wherein a halide is admixed with said
platelet-shaped substrate coated with TiO.sub.2 in an amount of from 0.1
to 40% by weight of the substrate coated with TiO.sub.2.
12. The process of claim 11, wherein said halide is admixed to said
platelet-shaped substrate coated with TiO.sub.2 in an amount of from 0.5
to 10% by weight of the substrate coated with TiO.sub.2.
13. The process of claim 11, wherein said halide is MgCl.sub.2, CaCl.sub.2
or CeCl.sub.3.
14. The process of claim 5, wherein the non oxidizing atmosphere is a
N.sub.2 or Ar atmosphere.
15. The process of claim 5, wherein the temperature is of from more than
600.degree. C. to 1100.degree. C.
16. The process of claim 5, wherein the mixture is heated for 10 to 60
minutes.
Description
CROSS REFERENCE TO RELATED APPLICATION
This is a 371 of PCT/EP93/00617, filed Mar. 16, 1993.
The present invention relates to a platelet-shaped colored pigment
comprising titanium dioxide, one or more suboxides of titanium, and an
oxide or oxides of one or more different metals and/or non metals.
BACKGROUND OF THE INVENTION
There is a continuously increasing demand for pigments with intense
pearlescent color and/or metallic luster in the field of paints, coatings,
inks, plastics, cosmetics and especially for exterior coatings. Therefore,
the development in the field of pigments aims at lustrous and hiding
pigments which can be new effect pigments or replace the metallic pigments
such as aluminum flakes with their known disadvantages. It is known that
coatings of TiO.sub.2 -layers on platelet-shaped substrates produce the
so-called pearlescent effect. For this kind of pigments it is possible to
control the interference color by changing the thickness of the TiO.sub.2
-layer. It is known from DE 3433657, U.S. Pat. No. 4,623,396 and EP
0332071 to use suboxides, e.g. suboxides of titanium, for the coating of
platelet-shaped substrates whereby for the reduction of the TiO.sub.2
ammonia gas is used.
However, the reduction of solid particles by a reducing gas is not suitable
for an industrial production, because the color of the product as a
function of the degree of reduction is difficult to control. It is
dependent on the size of the particles, the temperature, the gas flow and
the time of treatment. Furthermore special facilities for dangerous or
toxic gas are necessary. It is also known that such suboxides provide
functional properties such as electric conductivity.
JP-A-1-158077 discloses a pigment consisting of a titanium oxide layer
containing a dark color region on a mica core and a color tone adjusting
layer as covering layer comprising at least one of silicon oxide, aluminum
oxide and zinc oxide or a composite oxide thereof. The dark color region
is composed of a dark color metal oxide, such as titanium oxide or iron
oxide of lower order, of titanium nitride, titanium oxide or carbon black.
The pigment is manufactured in a first step by heating and reducing
titanium dioxide-coated mica flakes at a temperature of from 500.degree.
C. to 1000.degree. C. in a reducing gas; or by blending titanium
dioxide-coated mica flakes with titanium metal and heating the resulting
blend in a vacuum at a temperature of from 500.degree. to 1000.degree. C.
for a long time of more than 6 hours. The covering layer is deposited in a
second step in an aqueous medium by precipitating of silicon dioxide
hydrate on the first layer containing the titanium suboxides and drying or
firing the pigment. This additional coating improves heat stability of the
suboxide containing layer. However, the functional properties such as
electric conductivity of the first layer is shielded by this second layer.
The pigment has the disadvantage that it is manufactured in a complicated
two-step process which raises the price. The reduction in vacuum requires
expensive facilities and complicated operation and high temperature and
longer reaction time causes low production efficiency. Furthermore the
used titanium metal is expensive.
SUMMARY OF THE INVENTION
Accordingly, it is an object of this invention to provide platelet-shaped
colored pigments having improved heat stability without losing the
functional properties of colored layers which are producible in a simple
one-step process.
This object is solved according to the present invention by a
platelet-shaped colored pigment on the basis of a platelet-shaped
substrate which is covered by a coating layer containing TiO.sub.2, one or
more suboxides of titanium and an oxide or oxides of one or more different
metals and/or non metals. The concentration of said titanium oxides in the
coating layer is maximum in the proximity of the substrate surface and
gradually decreases towards the pigment surface and the concentration of
said oxide or oxides of one or more different metals and/or non metals is
maximum at the pigment surface and gradually decreases towards the
substrate surface whereby mixed phases of these oxides exist inside the
coating layer.
The different elements are preferably selected from alkali metals, alkaline
earth metals, B, Al, Si, Zn or Fe. Furthermore all other elements with
sufficient reactivity can be used.
The amount of the one or more different metals and/or non metals is from 1
to 50% by weight, preferably from 2 to 30% by weight, relative to the
amount of titanium in the pigment.
Furthermore this object is solved by a process for producing
platelet-shaped colored pigments by mixing a platelet-shaped substrate
coated with TiO.sub.2 with at least one solid reducing agent, preferably
an alkaline earth metal B, Al, Si, Zn, Fe, LiH, CaH.sub.2, Al.sub.4
C.sub.3, Mg.sub.2 Si, MgSi.sub.2, Ca.sub.2 Si or CaSi.sub.2 and heating
the mixture in a non-oxidative gas atmosphere at a temperature of more
than 600.degree. C. for more than 10 minutes.
As starting materials platelet-shaped substrates like mica, kaolin or glass
platelets which optionally may be coated with one or more metal oxide
layers, or metal or metal oxide platelets coated with TiO.sub.2 are used.
The particle sizes of the substrates are 1 to 500 .mu.m in diameter and
0.1 to 1 .mu.m in thickness. The materials are coated with TiO.sub.2
according to processes well-known in the art and described for example in
U.S. Pat. No. 3,553,001.
The TiO.sub.2 -layer has a thickness in the range of from 10 to 1000 nm,
preferably from 40 to 500 nm. The reduction reaction takes place in a
non-oxidative gas atmosphere such as N.sub.2, Ar, He, CO.sub.2, C.sub.x
H.sub.y, H.sub.2, NH.sub.3. N.sub.2 or Ar are preferred. In case of
N.sub.2 or NH.sub.3, TiN or TiON may be formed in addition to TiO.sub.2-x.
It forms mixed solid suboxides or oxide bronzes on the platelet-shaped
substrates as soft solid powders at temperatures of more than 600.degree.
C., preferably in the range from 700.degree. to 1100.degree. C. for more
than 10 minutes, preferably for 15 minutes to 60 minutes. Some examples
will illustrate the reactions:
##STR1##
As reducing agent fine powdered elements like for example Al, Si, Mg, Ca
and B or combinations thereof are particularly preferred. Furthermore
alloys of metals or metal borides, carbides and silicides can be used.
Well-known reducing agents like the alkali metals may be used in liquid or
gas phase.
Other reducing agents are hydrides like LiH or CaH.sub.2.
In addition, combinations of these reducing agents with each other are
possible.
The TiO.sub.2 -pigment and the reducing agent are mixed in a ratio from
200:1 to 5:1 preferably from 100:1 to 10:1. The obtained pigments exhibit
strong pearlescent color and/or metallic luster.
The color effect of the pigments can be controlled by changing
the particle size of the platelet-shaped substrate (smaller particles lead
to a soft silky luster, larger particles lead to a glittering luster),
the thickness of the Ti-oxides layer (interference color),
the kind of the solid reducing agent (low reduction potential yields grey
to blueish black, high reduction potential yields black to yellowish
black) and
the amount of the solid reducing agent.
The reduction reaction is accelerated in the presence of a halide,
preferably a chloride as pointed out in Table 1. LiCl, NaCl, KCl,
MgCl.sub.2, CaCl.sub.2, CuCl.sub.2, CrCl.sub.3, MnCl.sub.2, FeCl.sub.2,
FeCl.sub.3, COCl.sub.2, NiCl.sub.2 or CeCl.sub.3 are preferred. The
reaction temperature can be reduced in the presence of chloride by
150.degree. to 300.degree. C. In example I the calcining temperature has
to be 1000.degree. C. without the admixture of chloride in order to reach
a reaction. It is reduced to 840.degree. C. by admixing of CaCl.sub.2.
The amounts of the halide can vary from 0.1 to 40%, preferably from 0.5 to
10% relative to the platelet-shaped substrate coated with TiO.sub.2.
The products show a depth profile regarding the distribution of titanium
and the one or more different metals and/or non metals inside the coating
layer.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a depth profile of Iriodin 120, a pearlescent TiO.sub.2
-pigment manufactured by E. MERCK. The concentration of titanium on the
pigment surface is 22 atomic % contrary to the silicon concentration which
is only about 5 atomic %.
FIG. 2 shows a depth profile of the same pigment after the reduction with
metallic silicon according to example 1. The titanium concentration is
decreased to 2 atomic % and the silicon concentration is increased to more
than 28 atomic %. During the reduction reaction metallic silicon
penetrates into the TiO.sub.2 -layer and is oxidized to Si.sub.2. The
silicon concentration decreases continously in the direction to the
substrate and is about 9% in a depth of 30 nm.
FIG. 3 shows the distribution of titanium and silicon in the pigment
described in JP-A-1-158 077 beginning from the surface of the coating
layer in direction to the substrate. The known pigment has been
manufactured by a two-step process as described in the comparative
examples 1 and 2. The two pigments show a very different structure. The
known pigment has distinct layers. The top layer precipitated from an
aqueous medium containing approximately 100% of silicon dioxide is more
than 3 nm thick. In contrary, the pigment according to the present
invention does not possess any distinct layers. The concentration of the
components in the coating layer is gradually changing with the depth of
this layer.
A pigment which is used in an organic solvent system such as paint or ink
is often required to have a certain level of conductivity in order to
avoid the danger of explosion by electrostatic spark. Table 2 shows the
temperature resistance and the electroconductivity of the known pigment
after the first process step (reduction of TiO.sub.2 -layer with Ti metal;
PM 21-2) and after the second process step (precipitation of Si.sub.2 ; PM
21-3) and of the pigment according to the present invention (PM 21-1). The
pigment according to the present invention has a significantly better
electroconductivity than the pigment produced by the two-step process.
Additional coating with SiO.sub.2 (PM 21-3) reduces the conductivity.
Furthermore the pigments according to the present invention show a better
application behavior. That means better results regarding the humidity
test in car paint application and regarding the photoactivity test in
out-door application. Photoactivity test results are shown in Table 3. The
pigment according to the invention has been compared with known pigments.
If desired the pigment can be provided with high magneticity as shown in
Table 4.
The invention will now be described more specifically with reference to
examples thereof, as well as comparative examples, which are not intended
to limit the scope of the invention.
EXAMPLE 1
15 g of a TiO.sub.2 -coated mica powder, particle size distribution 5-25
.mu.m, exhibiting white mass tone with white reflection color
(Iriodin.RTM. 120; produced by E. Merck) and 1.5 g of Si powder, particle
size <150 m (from E. Merck), was mixed thoroughly in a 500 ml plastic
bottle.
The mixture was put into a quartz boat.
The boat was placed inside a quartz tube (inner diameter 5 cm, length 100
cm). Both ends of this tube were equipped with gas pipes, one for
introducing gas and the other for exhausting gas.
Then blowing of N.sub.2 gas into this tube was started at room temperature
with the flow rate of 0.25 1/min.
After 15 min., the tube was placed into an oven which was kept at
1000.degree. C., and maintained for 30 minutes.
The tube was put out of the oven and let cool down. Until the tube was
cooled down, the blowing of N.sub.2 gas was maintained. The calcined
powder was washed with water and dried at 120.degree. C. over night, and
then the powder was passed through a 40 .mu.m sieve.
To evaluate the color characteristics of the pigment produced according to
the invention, 0.9 g of each pigment sample is worked in 53.6 g of an
acrylic modified nitrocellulose lacquer. After homogenizing with a
propeller mixer at 1000 rpm for 10 min the dispersion is allowed to stand
for one hour to remove air bubbles. Then the pigmented lacquer is coated
with an applicator (500 .mu.m wet film thickness) on a block and white
card.
The visual evaluation of the color is expressed as masstone and
interference color. The masstone color is the observation out of luster
(45.degree./0.degree.) and the interference color is the observation at
reflection angle (22.5.degree./22.5.degree.).
The CIE Lab color coordinates are measured with Hunter Lab Color Meter
model D-25 under the conditions of 45.degree./0.degree. with white
background and 22.5.degree./22.5.degree. with black background. The
obtained powder exhibits blue black masstone with blue interference color
(coloristics see also Table 4).
By ESCA measurement with combination of Ar sputtering technique, depth
distribution of Si atoms in the coated layer of this pigment was
determined.
As shown above in FIG. 2, Si atoms penetrate into Ti-oxide layer more than
30 nm and the distribution of Si atom shows gradation of concentration
along the depth. X-ray diffraction of this powder indicates the presence
of .gamma.Ti.sub.3 O.sub.5 and SiO.sub.2 (quartz).
EXAMPLE 2
100 g of a TiO.sub.2 -coated mica powder, particle size distribution 5-25
.mu.m, exhibiting reddish white mass tone with green interference
reflection color (Iriodin.RTM.231; produced by E. Merck), 3 g of the same
Si powder as in Example 1 and 1 g of CaCl.sub.2 were mixed throughly in a
3 l plastic bottle. This mixture was calcined at 800.degree. C. for 30
minutes under N.sub.2 gas flow of 3.0 l/min. with the same manner as in
Example 1. The calcined powder was washed with water and dried at
120.degree. C. overnight, and then the powder was passed through a 40
.mu.m sieve.
The obtained powder exhibits bluegreen black masstone with bluegreen
interference color. This sample showed 7.5 k.OMEGA.. cm of powder
conductivity which is enough to avoid electrostatic spark (see Table 2).
Comparative Example 1
This comparative example demonstrates the reduction with metallic titanium
according to JP-A-1-158 077 as the first step of the two-step process.
100 g of the same TiO.sub.2 -coated mica as in Example 2 and 5 g of Ti
powder (particle size 150 gm, from E. Merck) were mixed throughly in a 3 l
plastic bottle.
This mixture was calcined at 1000.degree. C. for 30 minutes under N.sub.2
gas flow of 0.25 l/min. with the Same manner as in Example 1. The calcined
powder was washed with water and dried at 120.degree. C. overnight, and
then the powder was passed through a 40 .mu.m sieve.
The obtained pigment exhibits bluegreen black mass tone with blue green
interference color.
The sample showed a powder conductivity of 31.5 M.OMEGA..cm. Consequently,
the pigment according to the present invention has a significantly better
electroconductivity than the comparison pigment.
Comparative Example 2
As the second step of the two-step process described in JP-A-1-158 007
silicon oxide hydrate was deposited on the surface of the pigment obtained
according to Comparative Example 1.
50 g of the pigment was dispersed into 500 ml of deionized water with
stirring. During the reaction the stirring was maintained. The dispersion
was heated up to 90.degree. C. and the pH was adjusted by adding 5 wt %
NaOH aq. solution. To this dispersion 75 ml of 10 wt % Na.sub.2 SiO.sub.3
aq. solution was added at the rate of 2 ml/min. While keeping the pH at 9
by simultaneous addition of 1N HCl aq. solution. 62 ml of 1N HCl aq.
solution was needed.
The temperature and stirring were maintained for an additional hour and
then the mixture was cooled. The solid was filtered, washed with water and
dried at 200.degree. C. overnight. The obtained pigment exhibits bluegreen
black mass tone with bluegreen interference color.
ESCA analysis with combination of Ar sputtering technique indicates that a
more than 3 nm thick silicon oxide layer, covers the titanium oxide layer
(see FIG. 3).
The sample shows a powder conductivity of >125 M.OMEGA.cm. This value makes
clear that the conductivity of the first layer is shielded by the silicon
oxide layer.
EXAMPLE 3-14
Mixtures of a TiO.sub.2 -coated mica pigment and a reducing agent and in
some cases a chloride were prepared in the same manner as in Example 1.
The ratio of the reactants is listed in Table 4. The mixtures were
calcined under the conditions described in Table 4.
The calcined powders were washed with water, dried at 120.degree. C.
overnight and then passed through a 40 .mu.m sieve.
The appearance colors and measured color values are listed in Table 4.
All of these Examples exhibit grey to dark color indicating the formation
of suboxides by the reaction.
EXAMPLES 15-32
These Examples demonstrate the influence of halides which accelerate the
reduction reaction and which make it possible to lower the reduction
reaction temperature.
The samples were prepared in the same manner as in Example 1. The mixing
ratios and the calcination conditions are listed in Table 4.
The color appearance and the measured values are described in Table 4.
The colors of the pigments in the Examples 16-19 are darker than the color
of the pigment in Example 15. In this Example no halide was added. The
darker color indicates the reduction reaction was accelerated.
The colors of the pigments in the Examples 20-28 are dark indicating a
reduction reaction took place, but without a halide the reduction reaction
does not take place at such low temperatures.
The Examples 29 to 32 show that with decreasing amount of the halide in the
mixture the color of the pigment becomes lighter.
EXAMPLE 33
This Example demonstrates the production of a dark colored conductive
pigment.
15 g of TiO.sub.2 -coated mica pigment (the same as in Example 1) and 3 g
of an Al powder (particle size <250 .mu.m, from E. Merck) was mixed in the
same manner as in Example 1 and calcined at 1000.degree. C. for 30 minutes
under N.sub.2 gas flow of 0.25 l/min.
The calcined material was washed with water, dried at 120.degree. C. over
night and passed through a 40 .mu.m sieve.
The obtained pigment exhibits yellowish black mass tone with brown
reflection color.
The X-ray diffraction of this pigment indicates the presence of Ti.sub.2
O.sub.3, TiN (Osbornite syn) and A.sub.2 O.sub.3.
The electroconductivity of this pigment was determined as 20 .OMEGA..cm.
EXAMPLE 34
This Example demonstrates the production of a pigment with magnetic
properties. 15 g of the same TiO.sub.2 -coated mica pigment as in Example
2, 1.35 g of the same Si powder as in Example 1 and 0.15 g of CaCl.sub.2
were mixed in the same manner as in Example 1. The mixture was calcined at
1000.degree. C. for 30 minutes under N.sub.2 gas flow of 1.5 l/min.
The calcined material was washed with water, dried at 120.degree. C.
overnight and passed through a 40 .mu.m sieve. The obtained pigment
exhibits black mass tone with brown reflection color and magnetic
properties.
TABLE 1
__________________________________________________________________________
Example
TiO.sub.2 coated
Reduction
Mixing ratio
Gas Calcine
Color masstone/
No. mica pig.
agent pig./red./chl.
flow rate
temp.
interference
__________________________________________________________________________
I Ir. 123
Si/CaCl.sub.2
100/4/4
N.sub.2
840.degree. C.
blue black/
PM 11 0.25 l/min blue
comparison
Ir. 123
Si 100/4 N.sub.2
840.degree. C.
no reaction
0.25 l/min (white/white)
II Ir. 123
Al/KCl
100/1/0.25
N.sub.2
800.degree. C.
grey/white
PM 13-2 0.25 l/min
comparison
Ir. 123
Al 100/1 N.sub.2
800.degree. C.
no reaction
0.25 l/min
III Ir. 123
B/KCl 100/1/0.25
N.sub.2
600.degree. C.
light grey/
PM 12-4 0.25 l/min white
comparison
Ir. 123
B 100/1 N.sub.2
600.degree. C.
no reaction
0.25 l/min
__________________________________________________________________________
Ir. means Iriodin .RTM., a trade name for interference pigments,
manufactured by E. MERCK.
TABLE 2
__________________________________________________________________________
Process
TiO.sub.2 coated
Reduction
Mixing ratio
Gas Calcine
Electro-
Sample mica pigment
agent pig./red.
flow rate
temp.
conductivity*
__________________________________________________________________________
Example 2
Ir. 231
Si/CaCl.sub.2
100/3/1
N.sub.2
800.degree. C.
7.5 k.OMEGA. .multidot. cm
(PM 21-1) 3 l/min.
Comparative
Ir. 231
Ti 100/5 N.sub.2
1000.degree. C.
31.5
M.OMEGA. .multidot. cm
Example 1 0.25 l/min.
(PM 21-2)
Comparative
PM 21-2 is coated with SiO.sub.2.nH.sub.2 O
>125
M.OMEGA. .multidot. cm
Example 2
Na.sub.2 SiO.sub.3 + HCl .fwdarw. SiO.sub.2.nH.sub.2 O
(PM 21-3)
__________________________________________________________________________
*Specific restistance of pigment powder, resistance of pressed powder
between two metal pistons in a tube with 10 kg/3 cm.sup.2 was measured an
calculated according to following formula:
##STR2##
(R.sub.sp : specific resistance [.OMEGA. .multidot. cm]); R: measured
resistance [.OMEGA.]; A: crosssectional area of a tube [cm.sup.2 ]; d:
thickness of powder layer [cm])
TABLE 3
__________________________________________________________________________
TiO.sub.2 coated
Reduction
Mixing ratio
Gas Calcine
Color masstone/
Humidity.sup.1)
Photoactivity.sup.2)
Sample
mica pig.
agent pig./red./chl.
flow rate
temp.
interference
16 h/66.degree. C.
UV lamp, 24
__________________________________________________________________________
h
1 Ir. 103
Mg 100/3.8
Ar 800.degree. C.
dark grey/
A B
0.25 l/min silver
2 Ir. 103
Si/CaCl.sub.2
100/2/0.5
N.sub.2
900.degree. C.
grey/silver
B B
3 l/min.
Ir. 103
-- -- -- -- -- white/white
C C
3 Ir. 123
Si/B/KCl
100/4/1/0.5
N.sub.2
700.degree. C.
dark grey/
B B
3 l/min. silver
Ir. 123
-- -- -- -- -- white/white
C C
__________________________________________________________________________
.sup.1) Test system 1coat acrylicmelamine thermosetting paint. 4 wt %
pigment content based on total paint.
.sup.2) 1 phr pigment incorporated in Pb compound containing PVC plate.
rank
A: less degradation
B: fair
C: much degradation
Ir. means Iriodin .RTM., a trade name for interference pigments,
manufactured by E. MERCK.
TABLE 4
__________________________________________________________________________
Powder mixture Calc. conditions
Reduction
Mixing ratio Calcine
Example
TiO.sub.2
agent/
pig./red./
Gas temp.
Color masstone/
No. mica pig.
halide
halide flow rate
(30 min.)
interference
__________________________________________________________________________
1 Ir. 120
Si 100/10 N.sub.2,
1000.degree. C.
blue black/
(Be 462) 0.25 l/min.
blue
2 Ir. 231
Si/CaCl.sub.2
100/3/1
N.sub.2
800.degree. C.
bluegreen
(PM 21-1) 3.0 l/min. black/bluegreen
3 Ir. 120
Al 100/10 N.sub.2,
1000.degree. C.
black/
(Be 454) 0.25 l/min.
reddish white
4 Ir. 120
Mg 100/10 Ar, 800.degree. C.
black/
(Be 564) 0.25 l/min.
silver
5 Ir. 221
B 100/1 N.sub.2,
900.degree. C.
blue black/
(Hg 34) 0.25 l/min.
lilac
6 Ir. 120
Al.sub.4 C.sub.3
100/5 N.sub.2,
1000.degree. C.
blueish
(Hg 1) 0.25 l/min.
grey/silver
7 Ir. 120
Mg.sub.2 Si
100/5 N.sub.2,
1000.degree. C.
blueish
(Hg 8) 0.25 l/min.
grey/silver
8 Ir. 120
MgSi.sub.2
100/5 N.sub.2,
1000.degree. C.
blueish
(Hg 14) 0.25 l/min.
black/lilac
9 Ir. 120
Ca.sub.2 Si
100/5 N.sub.2,
1000.degree. C.
grey/silver
(Hg 15) 0.25 l/min.
__________________________________________________________________________
Color meter values
45.degree./0.degree.
22.5.degree./22.5.degree.
Electro-
Example
white background
black background
conductivity
No. L a b L a b tivity Magnetivity
__________________________________________________________________________
1 13.2
-1.3
-7.4
38.8
+4.6
-15.5
3.0 k.OMEGA.cm
None
(Be 462)
2 -- -- -- -- -- -- 7.5 k.OMEGA.cm
--
(PM 21-1)
3 13.6
-0.5
-0.8
37.7
+3.8
-0.9
-1.3
k.OMEGA.cm
Little
(Be 454)
4 18.8
-0.6
-1.0
41.6
+2.4
-2.2
1.8 M.OMEGA.cm
Little
(Be 564)
5 34.9
-2.0
-5.4
36.8
+20.3
-39.5
451 k.OMEGA.cm
Little
(Hg 34)
6 27.1
-2.9
-7.9
59.2
+0.5
-13.1
30 k.OMEGA.cm
Little
(Hg 1)
7 21.1
-1.7
-4.5
53.4
+2.1
-8.7
24.3
k.OMEGA.cm
Much
(Hg 8)
8 12.3
-0.3
-3.6
37.6
+3.9
-8.5
12.2
k.OMEGA.cm
Much
(Hg 14)
9 42.5
-2.7
-3.3
72.7
+1.5
-6.7
155 M.OMEGA.cm
Much
(Hg 15)
__________________________________________________________________________
Powder mixture Calc. conditions
Reduction
Mixing ratio Calcine
Example
TiO.sub.2
agent/
pig./red./
Gas temp.
Color masstone/
No. mica pig.
halide
halide flow rate
(30 min.)
interference
__________________________________________________________________________
10 Ir. 120
CaSi.sub.2
100/5 N.sub.2,
1000.degree. C.
blueish
(Hg 7) 0.25 l/min.
grey/silver
11 Ir. 120
LiH 100/5 N.sub.2,
1000.degree. C.
yellowish
(Hg 10) 0.25 l/min.
grey/silver
12 Ir. 123
Fe/CaCl.sub.2
100/5/5
N.sub.2,
800.degree. C.
yellowish
(PM 30-1) 3.0 l/min. grey/silver
13 Ir. 123
Zn/CaCl.sub.2
100/5/5
N.sub.2,
600.degree. C.
grey/silver
(PM 30-5) 3.0 l/min.
14 Ir. 123
Si/B/KCl
100/4/1/0.5
N.sub.2,
650.degree. C.
grey/silver
(MK 24) 0.25 l/min.
15 Ir. 221
Si 100/10 N.sub.2,
1000.degree. C.
yellowish
(Be 523) 4.0 l/min. grey/blue
16 Ir. 221
Si/LiCl
100/9/1
N.sub.2,
1000.degree. C.
darkblue/
(Hg 29) 1.5 1/min. darklilac
17 Ir.
221
Si/NaCl
100/9/1
N.sub.2,
1000.degree. C.
darkblue/
(Hg 18) 1.5 1/min. lilac
18 Ir. 221
Si/KCl
100/9/1
N.sub.2,
1000.degree. C.
darkblue/
(Hg 20) 1.5 l/min. lilac
__________________________________________________________________________
Color meter values
45.degree./0.degree.
22.5.degree./22.5.degree.
Electro-
Example
white background
black background
conductivity
No. L a b L a b tivity Magnetivity
__________________________________________________________________________
10 31.3
-2.9
-5.2
63.8
+0.9
-9.7
920 k.OMEGA.cm
Little
(Hg 7)
11 49.8
-0.3
+6.0
72.4
-2.1
-2.8
80.8
M.OMEGA.cm
Much
(Hg 10)
12 54.6
-0.6
+6.7
80.1
+1.8
-3.1
>628
M.OMEGA.cm
Much
(PM 30-1)
13 59.4
-1.2
+4.9
84.6
+2.2
-4.9
<628
M.OMEGA.cm
None
(PM 30-5)
14 39.2
-2.9
-2.5
76.2
+1.7
-10.9
2.0 M.OMEGA.cm
None
(MK 24)
15 52.5
-2.6
2.2 23.8
+0.8
-17.0
60 M.OMEGA.cm
None
(Be 523)
16 23.0
.+-.0.0
-7.6
34.5
+10.9
-20.0
176 k.OMEGA.cm
Little
(Hg 29)
17 24.5
+0.2
-8.2
25.3
+18.5
-28.4
45 k.OMEGA.cm
Little
(Hg 18)
18 25.2
.+-.0.0
-7.8
36.0
.+-.19.2
-30.4
212 k.OMEGA.cm
Little
(Hg 20)
__________________________________________________________________________
Powder mixture Calc. conditions
Reduction
Mixing ratio Calcine
Example
TiO.sub.2
agent/
pig./red./
Gas temp.
Color masstone/
No. mica pig.
halide
halide flow rate
(30 min.)
interference
__________________________________________________________________________
19 Ir. 221
Si/CaCl.sub.2
100/9/1
N.sub.2,
1000.degree. C.
black/
(Hg 17) 1.5 l/min. darkgold
20 Ir. 123
Si/MgCl.sub.2
100/3/1.5
N.sub.2,
800.degree. C.
bluegrey/
(PM 20-1) 3.0 l/min. blue
21 Ir. 123
Si/FeCl.sub.2
100/3/1.5
N.sub.2,
800.degree. C.
bluegrey/
(PM 20-5) 3.0 l/min. blueish silver
22 Ir. 123
Si/FeCl.sub.3
100/3/1.5
N.sub.2,
800.degree. C.
bluegrey/
(PM 20-6) 3.0 l/min. blueish silver
23 Ir. 123
Si/NiCl.sub.2
100/3/1.5
N.sub.2,
800.degree. C.
darkblue-grey/
(PM 22-5) 3.0 l/min. blue
24 Ir. 123
Si/CuCl.sub.2
100/3/1.5
N.sub.2,
800.degree. C.
grey/silver
(PM 22-6) 3.0 l/min.
25 Ir. 123
Si/MnCl.sub.2
100/3/1.5
N.sub.2,
800.degree. C.
grey/silver
(PM 22-7) 3.0 l/min.
26 Ir. 123
Si/CrCl.sub.3
100/3/1.5
N.sub.2,
800.degree. C.
blueish grey/
(PM 22-8) 3.0 l/min. blueish silver
__________________________________________________________________________
Color meter values
45.degree./0.degree.
22.5.degree./22.5.degree.
Electro-
Example
white background
black background
conductivity
No. L a b L a b tivity Magnetivity
__________________________________________________________________________
19 11.7
-1.1
-0.1
32.4
+2.1
+1.7
28 k.OMEGA.cm
Much
(Hg 17)
20 127.7
-2.6
-8.5
49.7
+1.9
-17.4
-- --
(PM 20-1)
21 26.8
-2.9
-8.1
59.6
+1.1
-17.0
-- --
(PM 20-5)
22 29.9
-3.2
-7.8
61.9
+1.0
-16.5
-- --
(PM 20-6)
23 18.4
-1.7
-7.7
44.9
+3.0
-16.9
-- --
(PM 22-5)
24 24.7
-3.0
-8.4
54.2
+1.5
-18.7
-- --
(PM 22-6)
25 27.9
-3.1
-8.6
60.0
+1.2
-18.2
-- --
(PM 22-7)
26 25.2
-2.9
-9.2
56.0
+1.4
-19.0
-- --
(PM 22-8)
__________________________________________________________________________
Powder mixture Calc. conditions
Reduction
Mixing ratio Calcine
Example
TiO.sub.2
agent/
pig./red./
Gas temp.
Color masstone/
No. mica pig.
halide
halide flow rate
(30 min.)
interference
__________________________________________________________________________
27 Ir. 123
Si/CeCl.sub.3
100/3/1.5
N.sub.2,
800.degree. C.
grey/
(PM 29-3) 3.0 l/min. blueish silver
28 Ir. 123
Si/CoCl.sub.3
100/3/1.5
N.sub.2,
800.degree. C.
darkblue-
(PM 29-6) 3.0 1/min. grey/blue
29 Ir. 123
Si/CaCl.sub.2
100/2/10
3.0 l/min.
800.degree. C.
blueish dark-
(PM 26-2) grey/bluesilver
30 Ir. 123
Si/CaCl.sub.2
100/2/5
3.0 l/min.
800.degree. C.
blueish dark-
(PM 26-3) grey/bluesilver
31 Ir. 123
Si/CaCl.sub.2
100/2/2
3.0 l/min.
800.degree. C.
blueish grey/
(PM 26-4) blueish silver
32 Ir. 123
Si/CaCl.sub.2
100/3/0.5
3.0 l/min.
800.degree. C.
lightgrey/
(PM 19-2) blueish silver
__________________________________________________________________________
Color meter values
45.degree./0.degree.
22.5.degree./22.5.degree.
Electro-
Example
white background
black background
conductivity
No. L a b L a b tivity Magnetivity
__________________________________________________________________________
27 27.1
-3.1
-8.6
59.1
+1.0
-16.3
--
(PM 29-3)
28 18.9
-1.8
-7.8
47.1
+2.6
-16.3
-- --
(PM 29-6)
29 26.0
-2.8
-9.8
54.6
+1.0
-17.4
-- --
(PM 26-2)
30 27.9
-3.2
-8.6
58.7
+0.8
-17.1
-- --
(PM 26-3)
31 31.2
-3.4
-7.6
62.8
+0.5
-14.9
-- --
(PM 26-4)
32 41.34
-2.95
-2.36
78.14
1.23
-8.97
-- --
(PM 19-2)
__________________________________________________________________________
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